System and method for tip-in knock compensation

Abstract

A method of controlling an engine, the method comprising of providing fuel having a blend to a cylinder of the engine, actively varying said fuel blend in response to at least an operating condition, and where during a transient operating condition, said blend is adjusted to increase a heat capacity of said fuel to reduce a tendency for knock.

The invention claimed is: 
     
       1. A system for an engine of a vehicle traveling on the road, the system comprising;
 a cylinder of the engine; 
 a first injector configured to directly inject into the cylinder; 
 a second injector configured to inject into a port of the cylinder; and 
 a controller for detecting a driver pedal tip-in condition, and increasing an amount of injection from the second injector. 
 
     
     
       2. The system of  claim 1  further comprising a first reservoir coupled to the first injector and a second reservoir coupled to the second injector, where the second reservoir is configured to hold an alcohol blend. 
     
     
       3. The system of  claim 2  further comprising a knock sensor, where said controller adjusts one of said first and second injector based on said sensor. 
     
     
       4. A method of controlling an engine, the method comprising:
 providing fuel having a blend to a cylinder of the engine; and 
 actively varying said fuel blend in response to at least an operating condition; 
 boosting intake charge inducted into the cylinder 
 where during a transient operating condition, said blend is adjusted to increase a heat capacity of said fuel to reduce a tendency for knock. 
 
     
     
       5. A method of controlling an engine, the method comprising:
 providing fuel having a blend to a cylinder of the engine; 
 actively varying said fuel blend in response to at least an operating condition; and 
 where during a transient operating condition, said blend is adjusted to increase a heat capacity of said fuel to reduce a tendency for knock. 
 
     
     
       6. The method of  claim 5  where said blend is actively varied by changing a mixing valve of to adjust an amount of one of a first and second fuel types. 
     
     
       7. The method of  claim 5  wherein said blend is actively varied by adjusting operation of at least one of a first and second injector directed to a cylinder of an engine. 
     
     
       8. The method of  claim 7  wherein said first injector injectors directly into the cylinder and said second injector injects into a port of the cylinder. 
     
     
       9. The method of  claim 8  wherein said transient condition includes a driver tip-in. 
     
     
       10. The method of  claim 9  wherein said blend is adjusted by increasing an alcohol content of said blend. 
     
     
       11. The method of  claim 10  wherein said first injector injects a ethanol blend. 
     
     
       12. The method of  claim 11  wherein said first injector injects ethanol. 
     
     
       13. The method of  claim 8  wherein said active variation occurs before an onset of knock. 
     
     
       14. The method of  claim 5  wherein said transient condition includes a rapid increase in engine load. 
     
     
       15. The method of  claim 1  further comprising increasing an alcohol content of a combusted mixture during said transient. 
     
     
       16. The method of  claim 15  further comprising boosting an intake charge directed to the engine.